companies marketing the device and technology says the federal law -- >> doesn't state it has to be received. >> reporter: they don't require text messages be used. georgetown university allowed news 4 cameras into their emergency centers. students download an app, they see trouble and alert police. the iphone cameras are seen on police tv monitors. >> we get their location, we get audio and we get video from the scene. >> reporter: it, too, is opt in. voluntary. private companies are marketing key fobs, a device that lights up with emergency messages hoping schools make it mandatory. >> most of us don't want to carry that. >> closed roads, open roads happen through here. >> reporter: d.c.'s homeland security has a silver bullet. the commercial mobile alert system, a push alert that hits every phone in d.c. with a text alert in the case of an emergency. universities have been called to inquire about it. the trouble is, they can only send alerts to the entire district of columbia. >> so many times they turn it off. >> howard university says they use text alerts for matters of an immediate thr